Somebody had to do this. This guy crunched up thousands of chess games from 1850 onwards to paint a picture of how chess has evolved since the middle of the nineteenth century. While some of these conclusions are to be expected, at least now we have some fancy graphs to go with them!
First Move Advantage
Draws Now More Common
For those who like yapping on about ratings, he also has a post on tournament games and ELO ratings.